Not long ago, the most high-profile thing a supermodel could do with her mobile phone was throw it at an underling’s head. How times have changed. Now, the world’s most powerful models run empires from their handheld devices and are as unlikely to be caught in a public tantrum as they are to eat a box of doughnuts.

Bella Hadid is one such smartphone supermodel. Keen students of Hadidology will be aware that the 20-year-old has 14.2 million Instagram followers. They will also know her backstory. Hadid broke into fashion two years after her sister, fellow model Gigi Hadid, became globally successful. Before that, the sisters were peripheral characters on glossy reality TV show The Real Housewives of Beverly Hills, in which their mother, Dutch-American model Yolanda Hadid, was a key player. Their father is millionaire real-estate developer Mohamed Hadid, who is originally from Palestine.

Much has been written about Bella being “cooler” than Gigi, a conclusion that is seemingly based on the visuals. Gigi is blond haired, blue eyed and smiley. Bella is brunette and looks more aloof, her face habitually arranged into a cheekbone-enhancing “fish gape”.

When we talk on the phone, she conveys a mix of Miss-World-contestant bubbliness and Thatcherite gusto. Her speech is peppered with giggles and gracious expressions of “thank you”. Her parents, she says, “started from nothing and worked to give us the life that we have, and now I guess all we can try to do is repay them”. That shouldn’t be difficult now. It is a sign of how obsessed the fashion industry has become with the Hadids that Bella’s new Max Mara Accessories campaign sees her replace last season’s face, Gigi. That, says Bella, is “crazy. You know, I think about this every day: I feel so genuinely lucky to have the family I do”. And later: “My mom always said there’s prettier girls in the world, there’s harder working girls in the world ... if you can’t be nice and work hard, somebody else will.”

My Instagram is like your Instagram. If I look cute then my friends are going to take a photo, but it’s not contrived

A post shared by Bella Hadid (@bellahadid) on May 17, 2017 at 1:24pm PDT

Bella suggests that her sunny nature does not always come across in photographs. “People meet me sometimes and say: ‘You’re so different to what I expected.’ People always tell me I seem mean or intimidating on social media. But I really love engaging with new people.” This is more than a simple case of bitchy resting face: “I feel uncomfortable, sometimes, smiling in front of the camera. It actually took me until probably this year to really understand my face.”

Hadid’s life is minutely documented in the little square boxes of Instagram. Often, she is working: reclining in a grey Max Mara overcoat or lit by flashbulbs backstage at Dior. Or she is hanging out with Kendall Jenner, Winnie Harlow or Emily Ratajkowski (together, they are Snapchat’s answer to the Rat Pack). Or, we see her striding past paparazzi with a fistful of shopping bags, or posting childhood photographs with her little brother, Anwar (caption: “Happy birthday my sweet angel. Your love and light is worth all of the stars in the sky!”)

This same formula has been deployed by celebrities since the golden age of Hollywood: an image of hard work and glamour peppered with humble, relatable moments, although the Hadid version contains rather more bikini selfies. “My Instagram is just like your Instagram,” she assures me (clearly, she has not seen the state of my feed). “If I look cute then my friends are going to take a photo, but it’s not contrived or planned.”

Still, she admits to feeling increasingly conflicted about how much to reveal. “In the beginning, I was very trusting,” she says. “Now I have taken a step back. So, I post things that are personal, but not too personal, things that still have that kind of look into my life ... but I guess I should hold off. I don’t know. It’s a very weird subject. You kind of feel it’s over-exposing sometimes. I guess there shouldn’t be that many people looking at one person constantly.” Her worst social media experiences have been “when you really get into the news. That is not a place I like to be”.

I feel like we are finally doing something for fashion that can make the world better

Strong foundations … Bella Hadid has her makeup applied ahead of a Dior fashion show in Oxfordshire. Photograph: Dylan Martinez/Reuters

The Hadids make headlines a lot, their love lives pored over by the tabloids (Bella recently broke up with Canadian singer Abel Tesfaye, AKA the Weeknd) while the broadsheets unpick the family’s heritage.

Gigi and her boyfriend Zayn Malik have been described, by this paper, as the US’s first Muslim pinup couple and a powerful force for good in the Trump era. The sisters were photographed attending the “No Ban No Wall” march in New York, after which Bella spoke about Islam for the first and – as far as I can find – only time, stating that she was “proud to be Muslim”. “My dad was a refugee when he first came to America,” she told Porter magazine. “So it’s actually very close to home for my sister and brother and me.”

At other times, however, the sisters have been criticised for not being Muslim enough. In April, Gigi was accused of cultural appropriation when she posed for Vogue Arabia in a hijab; her detractors argued that she only signalled her heritage when the prize was a magazine cover. In June, when Bella posted a topless Instagram picture, she received thousands of abusive comments about her religion.

Now, when I ask why she took part in the refugee-ban march, Hadid’s agent shuts down the conversation (“I think we are going to stay out of all that”). In an era in which protest is fashionable, when models with more niche online followings, such as Adwoa Aboah, use social media to promote feminism and activism, this is frustrating. Bella does talk about diversity in general, though, and about Halima Aden, who she says “changed fashion single-handedly” when she wore a hijab on the Max Mara catwalk in February. “It feels as though everything is finally coming together in the world of fashion; I feel like we are finally doing something for fashion that can make the world better.”

Bella wants to affect positive change, but she is still working out how. There is so much sadness in the world, she says, adding, in a slightly naive and jetlagged 20-year-old, supermodel kind of way, that she does not know where to start. “It’s just devastating: you see completely emaciated children and I’m supposed to go eat these incredible dinners when there are children who don’t even have water. Those are the things I want to help with.”

Bella describes her own brand as “being myself”, which sounds vague, but perhaps this lack of specificity allows people to project their own hopes on to her and explains why she has managed to charm so many people around the world. In 2011, Jonathan Franzen wrote that the internet was a world “so responsive to our wishes as to be, effectively, a mere extension of the self”. The same could be said of the biggest celebrities the internet has created, on to which any number of attributes can be projected. Does Bella’s dual heritage make her a unifying force in a divided US? Or is she simply someone who looks really great in a crop top? Perhaps she is a bit of both. Perhaps, like all great fashion models, she is whatever you would like her to be.